SCIENCE/EARTH SCIENCES GATORBYTES The University of Florida has an ambitious goal: to harness the of FloridaUniversity power of its faculty, staff, students, and alumni to solve some of society’s most pressing problems and to become a resource for the state of Florida, the nation, and the world. Sea levels are rising around the globe, and in Florida—with its 1,200 miles of coastline and mostly flat topography—this is of particular concern. The state depends on coastal cities, where 75 percent of the population lives and where more than four-fifths of its economic activity takes place. When econ- omists tally up the likely costs of rising seas, they rank Florida as the most RISE SEAS THE WHEN vulnerable state in the nation and Miami as one of the most vulnerable major cities in the world. When the Seas Rise takes us on an alarming journey from the dying coastal forests, where salt-killed tree trunks stand like sentinels of a retreating army, to the high tide–flooded streets of cities from St. Augustine to Key West. Meet the scientists at the University of Florida—researchers in biology, geol- ogy, entomology, horticulture, urban and regional planning, as well as other fields—who, along with experts around the state, are planning for the sea change already upon us and the greater changes to come. They are working around the clock to predict how global climate shifts will affect the state; to Gatorbytes protect drinking water and slow the effects of flooding; to develop new ways to farm; to save our butterflies, sea turtles, Key deer, and other endangered creatures; to preserve the state’s economy; and to help coastal dwellers plan future havens for the people and wildlife of Florida. The stories chronicled in Gatorbytes span all colleges WHEN THE and units across the UF campus. They detail the far- reaching impact of UF’s research, technologies, and innovations—and the UF faculty members dedicated to them. Gatorbytes describe how UF is continuing to build on its strengths and extend the reach of its efforts so SEAS RISE that it can help even more people in even more places. GLOBAL CHANGES AND LOCAL IMPACTS IBSN 978-1-942852-17-9 $14.95 UFPREEMINENCE.ORG 5 1 4 9 5 UFL.EDU 9 781942 852179 GATORBYTES WHEN THE SEAS RISE GLOBAL CHANGES AND LOCAL IMPACTS Heather Dewar CONTENTS 1. Nature’s Billboards 1 2. Obey and the Rock 11 Field Notes: On the Beach 32 3. Come Rain or Come Shine 37 Lab Notes: Hurricane Lore 47 4. Intelligent Tinkering 49 5. The Way Forward 71 Field Notes: Of Islands and Ice 85 Acknowledgments 91 Notes 93 1 NATURE’S BILLBOARDS A Tampa Bay surgeon was among the first Floridians to notice a sign that climate change is already making its mark on the state, though the doctor did not grasp the significance of the portent in his own backyard. Jack Putz, a University of Florida biology professor and an expert on tropical forests, took the doctor’s phone call in his Gainesville office in autumn 1991. The caller had a weekend home on a wild and beautiful marsh outside Yankeetown, near where the Withlacoochee River empties its fresh water into the Gulf of Mexico on Florida’s Big Bend. The house overlooks a nameless creek that meanders past forested islands of pines, oaks, cedars, and cabbage palms. “He said the palm trees were dying,” recalled Putz. “I joined forces with a forestry professor and a plant pathologist and paid the doctor a visit.” The three scientists expected to make a quick identification of the disease attacking the palms. Driving west from Gaines- ville, they took Highway 121 across the Williston sandhills, rel- ict dunes piled up before the last ice age when the world was warmer and sea levels were higher than today. On State Road 19, they cut across a platform of limestone rock that stretches to the Gulf, then followed State Road 40 to Yankeetown. · 1 · 2 · When the Seas Rise This swath of mostly protected land, held in state and fed- eral wildlife refuges and nature preserves, is about as close to wilderness as you will find along the Florida coast. Only a few hunting camps interrupt the flow of marshes and forests, creeks and bays, Gulf waters and wide skies luminous with sea- reflected light. Bald eagles outnumber people here. At last count, 13 pairs were nesting in the coastal forests around Yankeetown. Timbering flourished here in the mid-1800s, when loggers began cutting red cedar trees to make pencils and fragrant pan- eling for cedar closets. Others harvested palms to be made into brooms and brushes. But those industries died out about 100 years ago, and few people other than hunters and fishermen come here anymore. This is biologically rich country, home to at least 576 kinds of plants, including 16 species found nowhere in the world other than Florida and its borderlands. On this low terrain a few inches’ change in elevation cues a transition from marsh to palm- and cedar-girdled flats, and then to forests: red maple, ash, elm, live oak, and sweet gum, with a few cypress and sweet bay magnolias. Native slash pines mark the highest ground. The scientists spotted these subtle changes as they took a side road to the doctor’s place. “We looked around and saw that, yes, there were palm trees dying. But there were also dead and dying cedar trees. There were oak trees dying. There were pine trees dying,” Putz said. “We realized that because of the diversity of species affected, it probably wasn’t a pathogen. And it wasn’t just on that one property but on other forested islands as well.” Anxious to learn the extent of the die-off, the three scientists arranged a flight in a Florida Division of Forestry helicopter. “On a beautiful autumn morning we flew from just north of Tampa’s development all the way around the Big Bend to south of Tallahassee,” Putz recalled. Nature’s Billboards · 3 “The extent of forest loss along that coast was alarming. For mile after mile, you could see the bones of these dead trees and, in some places, salt marsh plants underneath them. The pattern of tree death varied, but the phenomenon was visible through- out the flight.” The swath of dead and dying trees was more than 60 miles long. “At first we thought it was storm-related,” Putz said. “What struck us was that the deaths were concentrated close to the coast. But what later emerged from our studies is that it is el- evation above sea level, rather than proximity to the coast, that determines how long trees survive.” Putz and his colleagues had discovered one early warning sign of human-made climate change. As people burn fossil fuels that emit carbon dioxide and other greenhouse gases, changes in the composition of Earth’s atmosphere are causing it to trap more heat. Warmer air leads to warmer seas. Since water ex- pands as it heats up, and since the planet’s glaciers and polar ice caps are shedding meltwater, the oceans’ water volume is increasing. Sea levels are rising along most of the world’s coastlines. In part it’s a natural phenomenon, brought about by irregularities in Earth’s orbit around the Sun that lead to predictable, millen- nia-long cycles of warming and cooling. Earth is still respond- ing to the end of the last ice age some 17,000 years ago. But this change has been speeding up throughout the indus- trial age, and seas are rising faster now than they have in re- corded history. As saltwater climbs up Florida’s shorelines, it brings a suite of changes—among them, the deaths of trees that can’t abide brackish water. In 1990, a U.S. Fish and Wildlife Service report predicted global warming would lead to a forest die-off along the Big Bend. A few years later that forecast was coming true. 4 · When the Seas Rise In spring 1992, the University of Florida researchers marked out 13 forest plots, mostly on islands in Waccasassa State Pre- serve a few miles north of Yankeetown. Once a week for five years, slogging through mud, bugs, storms, and spiky marsh grasses, they checked for flooding and tested groundwater for traces of salt borne on high tides from Waccasassa Bay. Brackish water turned up in nearly all their samples—as little as a tea- spoon per liter in plots that rarely flooded, but more than four teaspoons per liter, enough for a medicinal gargle, where floods came often. Once a year they measured every tree in every plot, record- ing its species, age, and whether seedlings grew at its feet. They cross-checked their work against Nature’s indicators: cattails, sawgrass, and white-flowering arrowhead growing where the water was fresh or nearly fresh; black needlerush, salt grass, and saltworts in brackish water. To find out what had happened in the decades before the study began, they turned to tide measurements taken since 1939 at nearby Cedar Key and concluded that tidal flooding had become more frequent. Before the 1950s even the lowest lying plots rarely flooded. But by the 1990s they were flooding as many as 26 times a year. The more often the tree islands flooded, the saltier the soil water got and the quicker the forests died. First to go were the salt-sensitive ash, elms, and maples. Live oaks and slash pines were next. Red cedars and cabbage palms held on the longest, but with increased soil salinity, they died as well.